International Journal of Advanced Research Methodology in Engineering & Technology,
Special Issue, March 2017, ISBN 978-1-63535-324-2
MODELING AND ANALYSIS OF SHELL AND
TUBE HEAT EXCHANGER WITH DIFFERENT
BAFFLE MODEL USING CFD
M.B.Aravind Shankar1, A.Arvind Raj1,
B.Aadthiyan1, P.Cinraj1
1-UG Scholars
Department of Mechanical Engineering,
M.Kumarasamy College of Engineering, Karur, India.
[email protected]
Abstract—The target of the venture is to dissect the warmth
exchange productivity of shell and tube warm exchanger with
various baffles. This venture exhibits an outline philosophy to
look at different parameters of warmth exchanger. Two
distinctive astound models are investigation with the assistance of
CFD and look at the outcomes. Baffles are utilized to build the
warmth exchange rate by coordinating the stream way of the
liquid inside the shell and tube warm exchanger. A shell and
tube warm exchanger is a class of warmth exchanger plans.
As its name suggests, this sort of warmth exchanger
comprises of a shell (an extensive weight vessel) with a heap
of tubes inside it. One liquid goes through the tubes, and
another liquid streams over the tubes (through the shell) to
exchange warm between the two liquids. Two liquids, of
various beginning temperatures, course through the
warmth exchanger. The liquids can be either fluids or
gasses on either the shell or the tube side. There can be
numerous minor departure from the shell and tube plan.
Ordinarily, the finishes of each tube are associated with
plenums (once in a while called water boxes) through
openings in tubesheets. The tubes might be straight or
twisted in the state of a U, called U-tubes.
Keywords—Heat
Exchangers,
Computational
Dynamics, Shell and Tube, Boundary Conditions
Fluid
I. INTRODUCTION (HEADING 1)
A baffle is designed to support tube bundles and direct the flow of
fluids for maximum efficiency. Baffles are used to hold tubes in
position (preventing sagging), both in production and operation.
They reduce the vibration in long tubes during transmission of
fluids. Prevent the effects of vibration, which is increased with both
fluid velocity and the length of the exchanger. Direct shell-side fluid
flow along tube field. This increases fluid velocity and the effective
heat transfer co-efficient of the exchanger. Computational Fluid
Dynamics are used to calculate the efficiency of different baffles
and compared with final results. Analysing of critical flows &
surface properties are quite easy with CFD. Heat exchangers are
devices that facilitate the exchange of heat between two fluids that
are at different temperatures while keeping them from mixing with
each other. A shell and tube heat exchanger is a class of heat
exchanger designs. It is the most common type of heat exchanger in
S.Padmavathy2
2-Assitant Professor
Department of Mechanical Engineering,
M.Kumarasamy College of Engineering, Karur, India.
[email protected]
oil refineries and other large chemical processes, and is suited for
higher-pressure applications. As its name implies, this type of heat
exchanger consists of a shell (a large pressure vessel) with a bundle
of tubes inside it. One fluid runs through the tubes, and another fluid
flows over the tubes (through the shell) to transfer heat between the
two fluids. Two fluids, of different starting temperatures, flow
through the heat exchanger. One flows through the tubes (the tube
side) and the other flows outside the tubes but inside the shell (the
shell side). Heat is transferred from one fluid to the other through
the tube walls, either from tube side to shell side or vice versa. The
fluids can be either liquids or gases on either the shell or the tube
side. There can be many variations on the shell and tube design.
Typically, the ends of each tube are connected to plenums
(sometimes called water boxes) through holes in tubesheets. The
tubes may be straight or bent in the shape of a U, called U-tubes. A
simple design of a shell and tube heat exchanger makes it an ideal
cooling solution for a wide variety of applications. One of the most
common applications is the cooling of hydraulic fluid and oil in
engines, transmissions and hydraulic power packs. With the right
choice of materials they can also be used to cool or heat other
mediums, such as swimming pool water or charge air. One of the
big advantages of using a shell and tube heat exchanger is that they
are often easy to service, particularly with models where a floating
tube bundle (where the tube plates are not welded to the outer shell)
is available. Baffles are used to increase the heat transfer rate by
directing the flow path of the fluid inside the shell and tube heat
exchanger. Baffles are flow-directing or obstructing vanes or panels
used in some industrial process vessels (tanks), such as shell and
tube heat exchangers, chemical reactors, and static mixers. Baffles
are an integral part of the shell and tube heat exchanger design. The
shell side outline of a shell-and-tube warm exchanger; specifically
the perplex separating, bewilder cut and shell distance across
conditions of the warmth exchange coefficient and the weight drop
are researched by numerically displaying a little warmth exchanger.
The stream and temperature fields inside the shell are settled
utilizing a business CFD bundle. An arrangement of CFD
reenactments is performed for a solitary shell and single tube pass
warm exchanger with a variable number of astounds and turbulent
stream. The outcomes are seen to be delicate to the turbulence
demonstrate determination. The best turbulence show among the
ones considered is dictated by looking at the CFD aftereffects of
warmth exchange coefficient, outlet temperature and weight drop
with the Bell–Delaware strategy comes about. For two puzzle cut
80
International Journal of Advanced Research Methodology in Engineering & Technology,
Special Issue, March 2017, ISBN 978-1-63535-324-2
values, the impact of the confuse separating to shell distance across
proportion on the warmth exchanger execution is researched by
changing stream rate.
II. COMPUTATIONAL FLUID DYNAMICS
CFD gives numerical estimate to the conditions that
administer smooth movement. Use of the CFD to dissect a liquid
issue requires the taking after strides. To begin with, the numerical
conditions portraying the liquid stream are composed. These are
typically an arrangement of fractional differential conditions. These
conditions are then discretized to create a numerical simple of the
conditions. The area is then isolated into little matrices or
components. At long last, the underlying conditions and the limit
states of the particular issue are utilized to explain these conditions.
The arrangement technique can be immediate alternately iterative.
Furthermore, certain control parameters are utilized to control the
joining, dependability, and exactness of the technique.
speak to such things as restricted supplies of liquid, surrounding
research facility conditions and connected weights emerging from
mechanical gadgets. By and large, a weight condition can't be
utilized at a limit where speeds are likewise indicated, since speeds
are affected by weight inclinations. The main special case is when
weights are important to indicate the liquid properties, e.g., thickness
crossing a limit through a condition of state.
IV. HEAT EXCHANGERS
Heat exchangers are gadgets that encourage the trading of
warmth between two liquids that are at various temperatures while
shielding them from blending with each other. Heat exchangers are
normally utilized as a part of practice in an extensive variety of uses,
from warming and aerating and cooling frameworks in a family, to
compound preparing and power plant.
V. BAFFLE PLATES
In this section we are for the most part worried with the
stream solver part of CFD. This part is partitioned into five segments.
In area two of this section we audit the general representing
conditions of the stream. In segment three we talk about three
standard numerical answers for the halfway differential conditions
portraying the stream. In area four we present the strategies for
fathoming the discrete conditions, in any case, this segment is
predominantly on the limited contrast strategy. What's more, in
segment five we examine different lattice era strategies and work
structures. Exceptional issues emerging because of the numerical
guess of the stream conditions are likewise examined and strategies
to determine them are presented in the accompanying segment.
Baffles are flow-directing or obstructing vanes or panels used in
some industrial process vessels (tanks), such as shell and tube heat
exchangers, chemical reactors, and static mixers.Baffles are an
integral part of the shell and tube heat exchanger design. A baffle is
designed to support tube bundles and direct the flow of fluids for
maximum efficiency.
Baffle cut:
Baffle cut is the tallness of the portion that is sliced in each bewilder
to allow the shell side liquid to stream over the baffle.This is
communicated as a rate of the shell inside diameter.Although this, as
well, is a vital parameter for STHE outline, its impact is less
significant than that of confuse separating.
III. BOUNDARY CONDITIONS
The type of the limit conditions that is required by any
incomplete differential condition relies on upon the condition itself
and the way that it has been discretized. Regular limit conditions are
characterized either in terms of the numerical qualities that must be
set or as far as the physical sort of the limit condition. The physical
boundary conditions that are commonly observed in the fluid
problems are as follows:
1.Solid walls: Numerous limits inside a liquid stream area will be
strong dividers, and these can be either stationary or moving
dividers. In the event that the stream is laminar then the speed parts
can be set to be the speed of the divider. At the point when the stream
is turbulent, notwithstanding, the circumstance is more mind
boggling.
2.Inlets: At an inlet, liquid enters the area and, consequently, its
liquid speed or weight, or the mass stream rate might be known.
Likewise, the liquid may have certain qualities, for example, the
turbulence portrays which should be determined.
3.Symmetry boundaries: When the flow is symmetrical about
some plane there is no flow through the boundary and the derivatives
of the variables normal to the boundary are zero.
4.Cyclic or periodic boundaries: These limits come in sets and
are utilized to determine that the stream has similar estimations of
the factors at identical positions on both of the limits.
Baffle models:
Baffles are used to guide the direction of the flow inside the shell and
also it support the tubes. Welding technique is used to fixed the baffle
models.
Following baffle models are,
Single segmental model:
5.Pressure Boundary Conditions: The capacity to determine a
weight condition at one or more limits of a computational district is
an imperative and helpful computational apparatus. Weight limits
81
International Journal of Advanced Research Methodology in Engineering & Technology,
Special Issue, March 2017, ISBN 978-1-63535-324-2
vi.
Support/Blanking baffles
The overall diameter of the baffle is 400mm. the cut section where
occurred at the length of 240mm.
Flower Baffle model:
The overall diameter of the baffle is 400mm.
CONCLUSION
We have experimented on Flower baffle model and identified
that, it has low pressure drop, increase in vorticity compared to the
ordinary segmental baffle plate. So we can use the flower baffle
plate for long time with better efficiency. The metal usage of the
baffle also decreases in large manner.
References
Types of baffle:s
Implementation of baffles is decided on the basis of size, cost and
their ability to lend support to the tube bundles.
i.
ii.
iii.
iv.
v.
Longitudinal Flow Baffles (used in a two-pass shell)
Impingement Baffles (used for protecting bundle when
entrance velocity is high)
Orifice Baffles
Single segmental
Double segmental
The shell side design of a shell-and-tube heat exchanger; in
particular the baffle spacing, baffle cut and shell diameter
dependencies of the heat transfer coefficient and the pressure
drop are investigated by numerically modeling a small heat
exchanger. The flow and temperature fields inside the shell are
resolved using a commercial CFD package. A set of CFD
simulations is performed for a single shell and single tube pass
heat exchanger with a variable number of baffles and turbulent
flow. The results are observed to be sensitive to the turbulence
model selection. The best turbulence model among the ones
considered is determined by comparing the CFD results of
heat transfer coefficient, outlet temperature and pressure drop
with the Bell–Delaware method results. For two baffle cut
values, the effect of the baffle spacing to shell diameter ratio
on the heat exchanger performance is investigated by varying
flow rate. [1].
Performance of heat exchangers with helical baffles, or
helixchangers, is discussed using the results of tests conducted
on units with uarious baffle geometries. An optimum helix
angle is identified at which the conversion efficiency for
converting pressure drop to heat transfer on the shell side of
helixchangers is maximized. Designs for standard industry
applications are optimized using the analysis of test results [2].
[1]
[2]
2010 Ender Ozden, Middle East Technical University, Turkey “Shell
side CFD analysis of a small shell-and-tube heat exchanger”.
2007 D. Kral and P. Stehlik “Helical Baffles in Shell-and-Tube Heat
Exchangers (Experimental Verification)”.
82